1. Field of the Invention
This invention relates to a magnetic disk and magnetic disk device provided with this disk for recording and reproducing data and programs by means of a magnetic head mounted on a floating head slider.
2. Description of Related Art
Computer systems for instance utilize a hard disk unit as the magnetic disk unit. The magnetic disk housed inside this hard disk unit is covered with a magnetic film on both surfaces and data is recorded or reproduced in a track configuration on this magnetic film by means of a magnetic head mounted on a floating head slider above both sides of the magnetic disk. The mechanism that drives the floating head slider with the magnetic head, and the drive section for the magnetic disk are incorporated beforehand inside the unit panel so that data is recorded at a relatively high density and the recorded data can be accessed at high speed.
The magnetic disk unit described below has been previously proposed as a hard disk unit by this applicant (in Japanese laid-open patent publication No. 6-259709 and U.S. patent application Ser. No. 08/331,588 applied for on Mar. 4, 1994, now abandoned, but continued as file wrapper continuation application Ser. No. 08/704,435). The magnetic disk housed in this hard disk unit has data record zones (hereafter "data zones") and control signal record zones (hereafter "servo zones") each formed in a radial configuration comprised of irregularities and containing data. More specifically, the data zones are concentric and the data tracks are formed of protrusions (projections) to record the data and guard bands to isolate adjacent tracks are formed of concavities (indentations). Further, gray codes to specify a particular data track, clock marks as a reference when generating a servo clock pulse and wobble marks (hereafter "servo patterns) for controlling the tracking of a magnetic head are formed on these servo zones. This servo pattern may be formed of protrusions or concavities.
At least one among these gray codes, clock marks and wobble marks is formed along the movement path (locus) of the magnetic head. The reproducing and recording of data by the magnetic head is controlled by means of the signal obtained from the reproduction of these gray codes, clock marks or wobble marks.
The magnetic head measures the amount of change in eccentricity of the magnetic disk by means of the signal obtained from the reproduction of these gray codes, clock marks or wobble marks and the record and reproduction of data by the magnetic head is controlled by the results of this eccentric deviation measurement.
In a hard disk device housing a built-in magnetic disk of this structure, the guard band for the data tracks is formed as a material concavity so that there is little possibility of reproduction of data from the guard band. Thus there is no longer a need to widen the guard band in order to reduce cross talk so that the track pitch can be narrowed and the recording capacity increased.
Additionally, since the gray codes, clock marks or wobble marks can be formed as protrusions or concavities along the movement path (locus) of the magnetic head, the positions for these codes can be placed with extremely high accuracy for utilization for example by optics technology so that even if the track pitch is narrowed, the data can be recorded accurately.